Spark ignition apparatus for internal combustion engines

ABSTRACT

Spark ignition apparatus for an internal combustion engine including a hollow casing rotatably supporting a shaft driven by the engine in use. A sensor is positioned within the casing, and is mounted for angular movement about the rotational axis of the shaft. The sensor is sensitive to the angular position of a member which rotates with the shaft. A housing is carried by the casing and receives the components of an electronic circuit which is operated in response to the output from the sensor. The electronic circuit in response to the output from the sensor breaks and restores an electric circuit through the primary winding of the ignition coil of the ignition system of the vehicle. Supported by the housing is a vacuum actuator the moving rod of which is coupled to the sensor. Thus the actuator which in use communicates with the inlet manifold of the internal combustion engine adjusts the position of the sensor relative to the casing of the apparatus in accordance with the pressure conditions in the engine inlet manifold.

United States Patent Longstaff-Tyrrell SPARK IGNITION APPARATUS FOR INTERNAL COMBUSTION ENGINES [75] Inventor: John Longstaff-Tyrrell,

Birmingham, England [73] Assignee: Lucas Electrical Company Limited,

Birmingham, England [22] Filed: Aug. 20, 1973 [21] Appl. No.: 389,498

[30] Foreign Application Priority Data Aug. 18, 1972 United Kingdom 38602/72 [52] U.S. Cl. 123/148 E; 123/148 R; 200/31 V [51] Int. Cl. F02P 3/04 [58] Field of Search..... 123/148 E, 146.5 A, 148 D;

200/31 A, 31 V, 31 DP, 25, 27 A, 29, 22

[56] References Cited UNITED STATES PATENTS 1,018,137 2/1912 Smith i. 200/27 A X 1,833,083 11/1931 Lehn 200/27 A 2,773,140 12/1956 Guernsey et al.. 123/1465 A 2,782,247 2/1957 Bales 123/148 D 3,289,020 11/1966 Frank et a1 i 310/70 R 3,304,926 2/1967 Maiden et a1. 123/148 E 3,328,614 6/1967 Falge et al 123/148 E X 3,370,190 2/1968 Neapolitakis 123/148 E X 3,581,725 6/1971 l-Iemphill et al.. 123/148 E 3,638,630 2/1972 Hetzler et a1. 123/146.5 A X 3,795,236 3/1974 Jukes et al. 123/146.5 A X 3,820,521 6/1974 Longstaff-Tyrrell..... l23/l46.5 A X FOREIGN PATENTS OR APPLICATIONS 371,920 3/1939 Italy 200/31 V Primary ExaminerCharles J. Myhre Assistant ExaminerTony Argenbright Attorney, Agent, or FirmHolman & Stern ABSTRACT Spark ignition apparatus for an internal combustion engine including a hollow casing rotatably supporting a shaft driven by the engine in use. A sensor is positioned within the casing, and is mounted for angular movement about the rotational axis of the shaft. The sensor is sensitive to the angular position of a member which rotates with the shaft. A housing is carried by the casing and receives the components of an electronic circuit which is operated in response to the output from the sensor. The electronic circuit in response to the output from the sensor breaks and restores an electric circuit through the primary winding of the ignition coil of the ignition system of the vehicle. Supported by the housing is a vacuum actuator the moving rod of which is coupled to the sensor. Thus the actuator which in use communicates with the inlet manifold of the internal combustion engine adjusts the position of the sensor relative to the casing of the apparatus in accordance with the pressure conditions in the engine inlet manifold.

4 Claims, 2 Drawing Figures US Patent Sept. 23,1975 3,906,918

FIG].

SPARK IGNITION APPARATUS FOR INTERNAL COMBUSTION ENGINES This invention relates to spark ignition apparatus for internal combustion engines.

Apparatus according to the invention includes a hollow casing, a shaft rotatable in the casing and driven by the engine in use, a sensor adjustably mounted within the casing for angular movement about the rotational axis of the shaft and sensitive to the angular position of a member rotating with said shaft, a housing carried by said casing and receiving components of an electronic circuit operable in use in response to the output from said sensor to break and restore an electric circuit through the primary winding of an ignition coil, and a vacuum actuator supported by said housing and coupled to said sensor, the actuator in use communicating with the inlet manifold of the internal combustion engine and adjusting the position of said sensor relative to the casing in accordance with the pressure conditions in the inlet manifold.

Conveniently said vacuum actuator is adjustably mounted on said housing so that a rest position of said sensor can be adjusted.

Desirably said sensor is part of a transformer and includes a pair of windings and said member includes a plurality of similar angularly spaced parts each part, when adjacent the sensor, altering the magnetic coupling between said windings and so altering the output of the sensor.

Preferably at least some of said components received by said housing are in heat exchange relationship with housing.

Desirably the casing is closed by an insulating cap carrying a plurality of terminals for connections to respective sparking plugs of the internal combustion engine and said shaft carries a distributor arm which rotates with said shaft and in use distributes electrical sparking pulses to said terminals in turn.

In the accompanying drawings,

FIG. 1 is a plan view of part of spark ignition apparatus in accordance with one example of the invention, and

HO. 2 is a side elevational view of the apparatus shown in FIG. 1.

Referring to the drawings, the apparatus includes a hollow cylindrical metal casing 11 within which is rotatably mounted a driven shaft 12. The shaft 12 is driven in use by the internal combustion engine with which the apparatus is associated and the shaft 12 carries a moulded synthetic resin cylinder 13 which retates with the shaft, and which includes, adjacent its periphery four parallel axially extending equi-angularly spaced ferrite rods 14. Within the casing 11 is an annular metal base plate 15 which is fixed to the casing, and through which the shaft 12 extends with clearance. Ro tatably mounted on the base plate 15 for movement about the axis of the shaft 12 is a timing plate 16 and carried by the timing plate 16 is a sensor 17. The sensor is mounted for movement towards and away from the axis of the shaft 12, so that the sensor can be set in the optimum position in relation to the periphery of the cylinder 13. Once set, it is not intended that the position of the sensor 17 should be adjusted, other than for the purpose of maintenance.

Secured to the exterior of the casing 11 is a generally rectangular metal housing 18. The housing 18 is secured to the casing 11 by screws one of which is shown at 19, the screws 19 extending through the wall of the casing 11, and co-operating with the base plate 15 to retain the base plate 15 in position within the casing 11. Slidably mounted on the housing 18 is a vacuum unit 21 which in use is coupled by way of a flexible conduit to the inlet manifold of the internal combustion engine. The vacuum unit 21 includes a diaphragm which is moved, in use, in response to pressure changes in the inlet manifold of the engine, and coupled to the diaphragm is a push rod which extends through the housing 18 and an aperture in the casing 11, and which is connected to the timing plate 16. Thus the timing plate, and therefore the sensor 17 are moved relative to the casing 11 about the axis of the shaft 13 in accordance with variation in the pressure in the inlet manifold of the engine.

One end of the casing 11 is closed in use by a moulded synthetic resin cap which is secured to the remainder of the casing 11 by means of hinged clips 22. The insulating cap carries four equi-angularly spaced terminals for connection to the four sparking plugs of the internal combustion engine, and the cap additionally carries a centre terminal electrically connected to a spring loaded contact within the cap which bears upon one end of a conductor carried on an insulating distributor arm 23 rotating with the shaft 12. During rotation of the shaft 12 the conductor of the distributor arm 23 passes close to each of said four terminals on the cap in turn. The centre terminal of the cap is electrically connected to the high tension terminal of a conventional ignition coil, and so receives sparking pulses, the sparking pulses being distributed by the distributor arm 23 to the spark plug terminals of the cap in turn, as the shaft 12 rotates.

The sensor 17 comprises an E-shapcd ferrite core two of the three parallel limbs of which terminate at their free ends adjacent the cylindrical surface of the cylinder 13. Each of the three limbs of the core is encircled by a respective winding, and so when one of the ferrite rods 14 is adjacent said two limbs of the core, then the magnetic coupling between the respective two windings is substantially increased. The three windings constitute part of an oscillator which in turn constitutes part of an electronic control circuit controlling current flow in the primary winding of the ignition coil of the spark ignition system of the internal combustion en gine. In addition to the oscillator, the electronic circuit includes an amplifier, and components of the oscillator and amplifier are carried by the hollow housing 18. Some of the components, for example a power transistor 24 and a power resistor 25 are secured to the exterior of the housing 18, and are in heat exchange relationship with the housing 18 so that these components can dissipate heat both by radiation to the atmosphere, conduction to the atmosphere, and conduction to the housing 18, and through the housing 18 to the casing 11. Desirably, the housing 18 and casing 11 between them carry all of the components of the electronic control circuit, and additionally carry terminals whereby the necessary electrical connections to a battery, and the ignition coil can be made. Thus in such an arrangement the apparatus described above can be substituted for the ignition distributor of a conventional spark ignition system.

As stated above the vacuum unit 21 is slidably mounted on the housing 18. ln order to permit the rest position of the sensor 17 relative to the casing 11 to be set, the vacuum unit 21 is provided with a screw threaded shank which extends into the housing 18, and mounted for rotation. but not axial movement within the housing 18 is a thumb wheel 26 in screw-threaded engagement with the shank of the vacuum unit 21. The vacuum unit 21 is held against rotation. and so rotation of the thumb wheel 26 moves the vacuum unit 21 and the sensor 17 relative to the casing 11. It will be appreciated. that if desired the screw-threaded shank of the unit 21 and the thumb wheel 26 can be dispensed with, the vacuum unit 21 being fixed in position relative to the housing 18.

The sensor 17 is connected to the remaining components of the oscillator by means of a flexible lead 27, and the arrangement of the electronic control circuit is such that the substantial increase in the magnetic coupling between said pair of windings of the sensor 17 when any one of the four ferrite rods 14 is adjacent the respective poles of the core of the sensor 17 causes the oscillator to operate, the output signal of the oscillator being amplified. and being used to switch off a transistor which is associated with the primary winding of the ignition coil. so breaking the electrical circuit through the primary winding of the ignition coil, and causing a sparking pulse to be generated in the secondary winding of the coil. When the ferrite rod moves out of the proximity of the sensor 17 the oscillator ceases. and the transistor is switched on so re-establishing the electrical circuit through the primary winding in readiness for subsequent operation by the next. adjacent ferrite rod 14. It will be appreciated that since it is the arrival of a ferrite rod adjacent the sensor which causes a sparking pulse to be produced, then movement of the sensor relative to the casing 11 about the axis of the shaft 12 will alter the ignition timing of the internal combustion engine.

I claim:

1. In an internal combustion engine having a plurality of spark plugs. an ignition coil. an inlet manifold. and means for distributing electrical impulses to said plugs in a predefined order. a spark ignition apparatus which comprises:

a rotatable shaft driven by said engine;

a hollow casing within which said shaft is rotatably mounted;

timing means rotatably mounted with respect to said shaft within said casing;

a sensor mounted to said timing means so as to be rotatably adjustable with respect to said shaft along with said timing means;

means coupled to and rotating with said shaft, said sensor being responsive to the angular position of said coupled means for generating output signals;

means connected adjacent to said casing for separately housing semiconductor electronic circuit component means for responding to said output signals from said sensor for opening and closing an electrical circuit through the primary winding of said ignition coil;

said semiconductor electronic circuit component means being mounted on said housing means which further serve to dissipate heat generated by said component means during use; and

a vacuum actuator supported by said housing means and coupled to said sensor. said actuator in communication with the inlet manifold of said engine for adjusting the angular position of said sensor relative to said casing according to the pressure conditions in the inlet manifold of said engine.

2. Apparatus as claimed in claim 1 wherein the vacuum actuator is adjustably mounted on said housing means so that a rest position of said sensor can be adjusted.

3. Apparatus as claimed in claim 1 wherein said sensor is part of a transformer and includes a pair of windings and said coupled means includes a plurality of similar angularly spaced parts each part. when adjacent the sensor. altering the magnetic coupling between said windings and so altering the output of the sensor.

4. Apparatus as claimed in claim 1 wherein the casing is closed by an insulating cap carrying a plurality of terminals for connections to respective sparking plugs of the internal combustion engine and said shaft carries a distributor arm which rotates with said shaft and in use distributes electrical sparking pulses to said terminals in turn. 

1. In an internal combustion engine having a plurality of spark plugs, an ignition coil, an inlet manifold, and means for distributing electrical impulses to said plugs in a predefined order, a spark ignition apparatus which comprises: a rotatable shaft driven by said engine; a hollow casing within which said shaft is rotatably mounted; timing means rotatably mounted with respect to said shaft within said casing; a sensor mounted to said timing means so as to be rotatably adjustable with respect to said shaft along with said timing means; means coupled to and rotating with said shaft, said sensor being responsive to the angular position of said coupled means for generating output signals; means connected adjacent to said casing for separately housing semiconductor electronic circuit component means for responding to said output signals from said sensor for opening and closing an electrical circuit through the primary winding of said ignition coil; said semiconductor electronic circuit component means being mounted on said housing means which further serve to dissipate heat generated by said component means during use; and a vacuum actuator supported by said housing means and coupled to said sensor, said actuator in communication with the inlet manifold of said engine for adjusting the angular position of said sensor relative to said casing according to the pressure conditions in the inlet manifold of said engine.
 2. Apparatus as claimed in claim 1 wherein the vacuum actuator is adjustably mounted on said housing means so that a rest position of said sensor can be adjusted.
 3. Apparatus as claimed in claim 1 wherein said sensor is part of a transformer and includes a pair of windings and said coupled means includes a plurality of similar angularly spaced parts each part, when adjacent the sensor, altering the magnetic coupling between said windings and so altering the output of the sensor.
 4. Apparatus as claimed in claim 1 wherein the casing is closed by an insulating cap carrying a plurality of terminals for connections to respective sparking plugs of the internal combustion engine and said shaft carries a distributor arm which rotates with said shaft and in use distributes electrical sparking pulses to said terminals in turn. 